Portable Power




About: The name Cat’s Science Club comes from my daughter Aly, whom I call Aly Cat. She inspired me to take my love of science, and the fun I have with my students, to as many people as I can. Both my daughters hel...

This power pack would be for emergency use, like when a storm knocks out the power, and would be very nice to have for camping.

Okay, Fat Cat saw this on youtube and thought we could do an instructable on it. We highly recommend that you check out the link to the video by KK's Boathouse. It is very well done and explains in great detail.


We are showing you the power pack that Fat Cat made.  We have been able to charge a phone, use the soldering iron, and have a shop light on all at the same time.

We are not responsible for any damage or injuries that may occur due to making and / or using the power pack. Be smart and be safe.

Step 1: Materials

Auxiliary Power Socket
Battery Box
-WalMart Marine Group 24-31
Butt Splice x2
Deep Cycle Battery
Drill Bit
-Or Hole Cutter
Fuse Holder
Ring Terminal x2
Utility Knife
Wire Cutters

Step 2: Socket

Place battery into battery box. Make sure that there is enough space on one side to attach the auxiliary socket. Place the lid of the battery box on temporarily. There is a hangover lip on the lid that is an ideal spot to put the socket under. The idea is to help keep rain off the socket. Open the auxiliary power socket package and take out the parts. The socket will have an universal mount that can be used to mark the hole that we need to drill. Put the mount where you will want it on the box. Mark the hole and drill. BE CAREFUL OF THE BATTERY! Use a utility knife to clean up lose plastic and to help make the hole bigger, if needed. The socket will unscrew to two parts. Push the socket through the hole (from the outside) and connect the back of the socket from the inside on the box.

Step 3: Connecting

Take note of where your positive (red) and negative (black) wires are connected to the socket. Take the positive wire and butt splice it to the fuse holder. Take the ring terminal and connect it to the other end of the fuse holder. Take the negative wire and connect the terminal ring.

Step 4: Connect Battery

Make sure that the negative wire will make it to the terminal. If not, try to spin the battery around. Add fuse to the fuse holder. Connect the positive (red) wire to the positive terminal of the battery and the negative (black) wire to the negative terminal of the battery. Close lid.

Step 5: Connect

Connect an inverter to change the DC to AC and plug in properly rated devices. Our inverter has an USB and two plugs.

Step 6: Hmmm

We are not electronic experts. Please use caution when building.

Fat Cat said he wanted to build a back up power supply for the sump pump in the basement. When tested it blew the 20 amp fuse and with a 30 amp fuse the inverter would shut down when the pump would try to kick on. We think his 300w inverter is to small. What do you think?

The 300w inverter worked well with a soldering iron, shop light, and charging an iPhone all at the same time.

How to recharge? Battery charger is what we have for now. We are thinking about a trickle charge solar panel but we need to figure that out still.

Please check out KK's Boathouse at http://www.youtube.com/watch?v=7Tf3fngKA-c .



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    57 Discussions


    5 years ago

    Consider Anderson power poles being added to the project as well. I'm a ham radio operator that operates emergency communications, and we all have our equipment on power poles, and it makes changing equipment out quick and easy. Also we always fuse hot and neutral, you can never have too much fusing. There's my 7 cents worth, it used to be 2 cents, but inflation you know...

    3 replies

    lol thanks for the cents.

    We will have to investigate the power poles.

    Why fuse both hot and neutral? This (electronics) is relatively new to us and we are learning as much as we can from people like you.



    Power poles are a stupid-easy way to avoid all the issues the cigarette lighter causes. But for the inverter, especially if you go over 15A on the DC side (180w) you may want to just take the inverters input cables and wire them directly to the battery. The off switch built in to the inverter will keep it from trickle draining, and it will be much less likely to heat up and start a fire.
    If you still want it to be removable, make sure the gauge going to the power poles matches or is thicker than the included wires, and that the power pole is rated for higher amps than the inverters peak draw. Especially since connecting the inverter outside allows the battery box to be closed and sealed, trapping heat inside.

    Its more important on vehicles to earth the negative if you have a connection from a radio or something to another grounded point on the car. What can happen is if there is a short somewhere else, the current can end up going thru your radio, then the antenna cable and out to the chassis where the antenna is mounted, putting high currents thru the antenna coax, and the negative cable to the radio.

    Same thing can happen in car audio when you have a shield on the RCA cables to the amplifiers which are grounded at both the amp and head deck. A lousy ground on the amp (which is common with self-installs) will have excess current going down the RCA cable, via the internals of the head deck and out to ground, usually smoking up the headdeck (or worse, the RCA cable) in the process. That is why most head decks have a fuse in them between the RCA's ground and the power ground.

    And the power poles are _great_ connectors for casual DC use like this, Much more capable of a reliable connection than those awful cigarette lighter sockets which will usually heat up and then slip out at less than 10 amps.


    3 years ago

    Does the socket work 2 ways as in charge and discharge? In other words can you charge the battery through the same port you us to charge your devices? Can you have 2 sockets for pass-through charging?


    4 years ago

    Thank you for this Instructable


    4 years ago on Step 6

    For solar, I just use the harbor freight 1.5 watt solar battery charger on my portable power supply. I just plug the cigar lighter adapter into the 12 volt outlet on the power supply just like in a car. I've got the solar panel in my van rear window and my power supply sits conveniently in the back ready and charged.


    5 years ago on Introduction

    sumps have, as a general rule, fairly powerful ac engines. A 300 watt inverter would not be a good choice for powering something like a sump, even twice as large would not give you any room to use other devices. A KW inverter might be a good choice. You might want to consider one that has circuits that smooth the output of the inverter to be closer to a sinusoidal wave form. Some AC devices do not operate well on the square wave that most less expensive inverters output, fridges, some pumps, ac units, some washer & dryers for example. If your aim is to run simple lighting, small appliances or tools or laptops (not sure how the power supplies in full sized desktops would take to inverters. I do know that many are pretty hefty as far as the power supplies go requiring several hundred watts for their own use, ) than the smaller inverters will do nicely.

    2 replies

    Reply 5 years ago on Introduction

    That's curious.....wonder why. Inverters are at best specialty power supplies which a unit will power up on it or not. A loss of a specific driver really is a curious thing to have happen.


    5 years ago on Step 6

    the idea is good (not new but nice box) but i don't understand your way of thinking: there is plenty of place left inside the box, so why didn't you embeded the dc/ac changer and the 5V outs directly in, with some interuptor to be sure they don't drain any energy wile not using? (may be whith a fan to cool and an open hole , that's all and you would have all in one ! (and adding those parts in the room left, it would also stabilise the center of gravity that is completely deported with your position of the batery: i mean it is not centered...) (sorry for the english, i'm french)

    2 replies

    Thanks for the comments and suggestions. We are learning all the amazing ways electronics, power, energy, ... work. It seems the possibilities are endless. What were we thinking? We were thinking - I wonder if this will work ;-) or will Fat Cat set the house on fire lol.

    well, it's sure that using lead acid batteries, is not the safest, but the powerest !
    but not to have them charging in your bedroom or rest room, for sure ! :)


    5 years ago on Introduction

    Nice Instructable, thanks! ;-)

    As the battery already has a carrying handle, maybe you could make a suitable hole in the battery box lid or remove the handle and refit it to the box to make it easier to carry.

    If you're going to recharge iPhones etc, it would be much more efficient to use a 12v (battery voltage) - 5v converter (as shown in the photo with Step 5).

    2 replies

    The box comes with a strap and has a place to hold onto on the sides. We also we thinking that the box would keep rain water off. Putting a hole on top would reduce that :-)

    Fat Cat says he is going to use it for emergency lighting for now. We just put our phone on it to show the possibility.

    Thanks for the ideas and thoughts!

    if u look up l.e.d. bulbs on alibaba.com u'ill be able find pretty much what u need there. it may take up too 3 weeks or so . but uill get them


    5 years ago on Introduction

    This highlights expense of storing power, the batteries. Huge amount of back-ups, UPS, etc. No cheap source of storing adequate back-up power. We peons don't have the capital for large amounts of dedicated lead.

    2 replies

    5 years ago on Step 6

    Several years ago I was looking for a similar project for portable power while camping and could not find one anywhere. I ended up buying a portable power pack, which is now inoperable. I like this project and I want to explore connecting two or more batteries for more power during power outages.